Strange Central Heating / Radiators issues

[fixitflav]

I've a feeling that pump is faulty or the impeller & maybe the pump ports are full of sludge, I would switch off the boiler, shut the isol valves on either side of the pump, remove the four stud bolts from the pump and lever it up & out carefully, inspect for sludge build up in the pump ports, get a tie wrap and push it through each impeller vane to prove clear.

Agreed, I had a problem a few years ago. Had a slight kettling noise when system hot. Didn't suspect the pump but eventually it started to vibrate badly, so I replaced it (a stainless disc at the eye of the imperller had come adrift). The new pump cured the noise completely and when I looked into the old one, the impeller, 2 discs about 2mm apart, was solid with crud.
But OP - be careful releasing the water when you dismantle it. I did something similar on an earlier occsasion, can't remember the details but I got water in the junction box somehow and the RCD kept tripping. I had to set up a hairdrier on it for an hour or 2 to cure it.

 

[scotthud]

ok done that it went from 22W to 20W

 

[Johntheo5]

There is definitely something up with that pump, 20/22W on CP2 means the pump theoretically anyway is pumping nothing but it must be circulating something if the HW cylinder & (some) rads are heating up?, I would remove the pump head as suggested above.

Just confirm that this is your pump, a 6M.

 

[scotthud]

Looks the same this is mine.

 

[Johntheo5]

Well, you will have to check out the condition of that pump, I would remove the head and inspect it before throwing a new pump at it, how old is it?

 

[scotthud]

a few years now it was swapped from the original pump awhile back by British Gas, when it gets warm, ill have a look at taking pump off, unless it goes to crap before, what sort of pump should i be looking at to replace this one with at some point, 14 Radiators 6 up 8 down.

 

[Johntheo5]

6M Dab Evosta 3 which also displays the flowrate as well as the power. OR like my own, a 6M Wilo Yonos Pico, probably a bit cheaper but a very nice quiet pump, mine is 5 years old.